1. Technical Field
This invention relates to trailer hitches for hitching a wheeled trailer behind a towing vehicle. More particularly, it relates to hitches which automatically align and lock the trailer to the hitch, and which distribute the unbalanced weight of the trailer between forward and rearward wheels of the towing vehicle.
2. Description of the Prior Art
Conventional ball and socket type trailer hitches are in common use for towing trailers behind passenger and light utility vehicles. The conventional ball type trailer hitch comprises a downwardly opening, substantially spherical cavity or socket at the distal end of the front tongue of the trailer, and an interfitting upstanding spherical ball rigidly supported on and spaced rearwardly from the rear of the towing vehicle. When the ball is secured within the cavity in the tongue of the trailer, the trailer can be towed behind the vehicle.
The process of coupling a trailer and towing vehicle using a conventional ball and socket type trailer hitch is relatively complicated, and usually requires two people. First, the trailer's tongue must be raised above the level of the vehicle's ball. This is typically accomplished using a support jack mounted on the tongue. Next, the vehicle must be maneuvered into position with the ball directly below the cavity of the tongue. This procedure typically requires one person to operate the vehicle and another to direct the vehicle operator to maneuver the vehicle in one direction or the other until the ball is in position. Once the ball is positioned properly, the trailer's tongue is lowered, again using the support jack, until the cavity encloses the ball and the entire load on the tongue is carried by the vehicle. Finally, a safety mechanism is engaged to securely lock the ball within the cavity. It will be appreciated that the process described above can be quite time-consuming, even when performed by two experienced persons. When attempted by a single person, the process of coupling a trailer to a towing vehicle via a conventional ball and socket type trailer hitch is extremely difficult, if possible at all.
A major disadvantage of the ball and socket type trailer hitch is that it transmits only axial forces between the towing vehicle and the trailer. The ball and socket is not capable of transmitting rotational moments. This deficiency causes the trailer hitch to sag downwardly if the front end of the trailer is overloaded, thereby overloading the rearward wheels of the towing vehicle. Several designs have been offered to overcome this deficiency in the ball and socket hitch by creating a moment bearing connection through the hitch. These prior art devices commonly add one or more members connecting between the trailer tongue at a point rearwardly of the socket and the support for the ball at a point vertically downwardly from the ball. These additional members transmit axial forces or rotational moments to the ball support, thereby allowing the hitch to transmit rotational moments around a transverse horizontal axis between the vehicle and the trailer. A major disadvantage of these prior art weight distributing hitches is that each time the trailer is hitched to the towing vehicle, the additional members which distribute the unbalanced weight of the trailer to the forward and rearward wheels of the vehicle must be securely attached to the ball support, and then adjusted until the unbalanced weight is distributed properly.